Method for manufacturing or for repairing a component of a rotary machine as well as a component manufactured or repaired using such a method

ABSTRACT

A method for manufacturing a component of a rotary machine, the component extends in an axial direction and a radial direction vertical thereto, and has an inner channel, extending from a first end in a center of the component to a second end at a radial limiting surface of the component and which is partially closed. A blank includes the center of the component and is limited by an outer surface in the radial direction. The maximum dimension of the outer surface in the radial direction is smaller than the dimension of the limiting surface in the radial direction, A first subtractive process step is performed such that a part of the channel is manufactured by a machining process, with the part extending from the first end of the channel to the outer surface of the blank. Afterwards the channel is finished by a build-up process on the blank.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to European Application No. 16190145.9,filed Sep. 22, 2016, the contents of which are hereby incorporatedherein by reference.

BACKGROUND Field of the Invention

The invention relates to a method for manufacturing a component of arotary machine. The invention further relates to a method for repairinga component of a rotary machine, as well as to a component of a rotarymachine manufactured or repaired using such a method.

Background of the Invention

In the manufacturing of rotary machines, such as e.g. pumps, turbines,compressors, compactors or expanders it is known to elaborate rotatingrotors, pump impellers, impellers as well as stationary diffusers orguide wheels as a component out of a blank by a machining process or bya cutting process, for example by milling. In doing so, the blank can bepresent as a solid material or can already be preprocessed by a primaryshaping process.

Such a method is known from EP-B-2 012 957, for example. The methodproposed in this reference allows the machining manufacturing of thecomponent, that is to say that the component is at least essentiallybrought into the desired final form as a whole out of the blank by amachining device. The assembling of preprocessed parts of the component,for example by welding, is no longer necessary with such integralmanufacturing. This is particularly advantageous because welding seamsor other joints can be a weak spot at highly loaded parts of thecomponent in the operating state, the weak spot can be the cause of acrack or another damage of the component, for example due to corrosion.

SUMMARY

Hence a machining manufacturing without assembling individual parts isadvantageous, in particular, in the case of highly loaded components.That is why, such components as, for example rotors (impellers) forpumps are made of solid material, depending on the application, e.g. ofhigh-strength stainless steels, super alloys, other suitable metals ormetal alloys or also of non-metallic materials, for example ceramicmaterials, and the vanes and channels of the impeller are elaborated outof this material by cutting processes, for example by milling.

As already explained in EP-B-2 012 957, sometimes a machiningmanufacturing of the component as a whole is not possible for purelygeometrical reasons. This can be the case, for example, when the rotors(impeller) are designed as covered or closed impellers. In such adesign, the impeller comprises a shroud, on which the vanes are arrangedand also a cover plate covering the vanes completely or at leastpartially at the side facing away from the shroud. Hence, at leastpartially closed channels are formed between the vanes, the channelseach extending from the center of the impeller to its outer radiallimiting surface.

Even if considering that these channels could be milled out of the blankor processed by machining on both sides, respectively, that means fromthe interior of the impeller and also from its radial limiting surfaceby a machining device that geometry is subject to limitations and inmany cases machine manufacturing as a whole is impossible or at leastuneconomic.

In such cases, if it is no longer possible or practicable to mill theimpeller as a whole out of solid material for purely geometricalreasons, it is the state of the art to elaborate initially the shroudand the vanes out of a blank by machining. Then, the channels betweenthe vanes are completely open channels, which can be manufactured in asimple way. Afterward the cover plate is placed and joined to the shroudor the vanes, respectively, for example by welding.

Alternatively, it is also known, to manufacture the areas of thechannels, which cannot be milled, by an eroding method, for example byelectrical discharge machining (EDM: electrical discharge machining).However, these methods are generally comparatively slow and expensive.

It is also state of the art to manufacture such components having innerchannels by casting, wherein the inner channels are manufactured by anappropriate design of the mold or of the casting core, respectively.However, a cast component has the disadvantage that defects can ariseduring casting, for example in the structural conditions, havingnegative effects on the resilience and the stability of the component.Additionally, the surface qualities that can be achieved as well as thedimensional accuracy of areas, which cannot be milled are normallylimited during the casting process.

In EP-A-2 669 042 a method for a machining manufacturing of a closedimpeller is proposed, dividing the component (impeller) to be processedin two sub-volumes, which meet at a separating surface. As a result, thesub-volumes are defined such, that the separating surface comprises orintersects no limiting surfaces of the channels and that the channelscan be elaborated by a machining method, for example by milling, as awhole out of the first sub-volume later comprising the completedchannels. The second sub-volume, being then only a part of the coverplate, is either manufactured as a separate part and joined to the firstsub-volume after finishing or the second sub-volume is built on thefirst sub-volume by an additive processing method, for example, bybuild-up welding. Thus, it should be possible to manufacture thechannels completely by machine manufacturing. However, this method isstill subject to geometrical limitations.

This problem explained by closed impellers also present with othercomponents having an inner channel, which position or geometry is such,that a machining manufacturing as a whole is not possible and notpracticable, in particular for geometrical reasons. Examples mentionedhere are closed guide wheels, diffusors or also cooling channels inturbine blades, for example for cooling air.

Based on this state of the art, it is therefore an object of theinvention to provide another method for manufacturing a component of arotary machine, which component has at least one inner channel, by whichmethod, in particular, such components can be manufactured which do notallow machining manufacturing of the channel as a whole for geometricalreasons. Furthermore, the invention is expected to propose acorresponding component.

The objects of the invention meeting this problem are characterized bythe features disclosed herein.

According to one embodiment of the invention, a method for manufacturinga component of a rotary machine is proposed, the component extending inan axial direction as well as in a radial direction vertical thereto andhaving at least one inner channel, which extends from a first end in acenter of the component to a second end at a radial limiting surface ofthe component and which is at least partially closed, wherein a blank isprovided, comprising the center of the component and which blank islimited by an outer surface in the radial direction, wherein the maximumdimension of the outer surface in the radial direction is smaller thanthe dimension of the limiting surface in the radial direction, and inthat further a first subtractive process step is performed wherein apart of the channel is manufactured by a machining process, with thepart extending from the first end of the channel to the outer surface ofthe blank and in that afterwards the channel is finished by a build-upprocess on the blank.

Thus, the method according to the invention combines a subtractiveprocess, wherein material is removed from the blank, with an additive orbuild-up process, wherein material is applied, in an advantageousmanner. In this case, only a part of the channel is manufactured by amachining process, as the rest of the channel is generated by a build-upprocess. Due to this combination, it is possible to generate a channelwith—at least almost—any desired geometry.

Here a build-up process is a process, wherein the process takes placedirectly out of a shapeless or a neutrally shaped material, for exampleby melting.

As the dimension of the outer surface of the blank in the radialdirection is smaller than the dimension of the limiting surface of thefinished component in the radial direction, particularly the radialexterior parts of the component are manufactured by the build-upprocess, for example the part of the channel adjoining the limitingsurface and which part comprises the second end of the channel. Thisbuild-up process in the radial direction has a particularly advantage,that then usually no or only slightly overlapping structures have to bemanufactured during the build-up process, which is particularlyadvantageous regarding the procedural aspects.

As the blank is not processed by casting, the blank may advantageouslyinclude a forged material, which is then processed by machining. Alladvantages of the forged material are maintained by the machiningprocess. In doing so, at least the port of the channel into the centerof the component, that means its first end, as well as the port of thechannel into the outer surface of the blank is manufactured by machiningin the first subtractive process step.

Additionally, the part of the channel extending from the first end ofthe channel into the outer surface of the blank is manufactured bymachining in the first subtractive process step. Hence only one part ofthe channel is finished after completing the first subtractive processstep, the channel starting in the center of the blank or of thecomponent, respectively, and extending to the port into the outersurface of the blank. The first subtractive process step may eithercomprise a milling from the outer surface of the blank or a milling fromthe center of the blank. In particular it is also possible, that thefirst subtractive process step comprises both a milling or a machiningprocess, respectively, out of the center and also a milling from theouter surface of the blank.

After completing the first subtractive process step, the channel isfinished by a build-up process and the component is brought into itsfinal form.

In a preferred embodiment, the component comprises a plurality of innerchannels, each of which extends from a first end in the center of thecomponent to a second end at the radial limiting surface of thecomponent, wherein adjacent channels are respectively separated by aseparating wall, wherein in each case one part of the channel ismanufactured of each channel in the first subtractive process step, withthe part extending from the respective first end of the channel into theouter surface of the blank and wherein each separating wall and eachchannel is only finished by the build-up process. Though it isparticularly preferred if the port of each channel in the outer surfaceof the blank is designed that way in the first subtractive process step,that the port of the respective channel is already designed as a closedone. Then in each case these ports present all-site limited openings inthe outer surface of the blank.

Preferably, the blank is a solid, and in particular a rotationallysymmetric, body. But a cylindrical axial and through bore can preferablybe disposed in the center of the blank, which bore is used, for example,to fix the finished component on a shaft, e.g. on a driveshaft of apump. i.e. the blank preferably has a central bore before the firstsubtractive process step, which bore is arranged radially inwardly such,that in the finished state of the component each first end of a channelbeing arranged in the center is separated from the central bore by anannular body.

According to a particularly preferred embodiment, the first subtractiveprocess step is performed in such a manner, that after completing thisstep, the outer surface of the blank comprises a contiguous annular areacovering the confluence of each channel into the outer surface. Then ineach case these ports are all-site limited openings in the outer surfaceof the blank. This has the advantage, that in particular the contiguousannular area as well as the areas of the outer surface between the portsform a particular good basis, on which the build-up process can beginafterward.

The build-up process is preferably performed layer by layer. So it ispossible, that each layer is vertically oriented to the radialdirection. Of course, it is also possible to apply the layers in otherorientations, in such a way, that the respective surface normal of thelayer is obliquely oriented to the radial and/or axial direction. Thatis to say, the additive buildup on the blank is made by a successiveapplication of material layers after finishing the first subtractiveprocess step, until the component is finished. The application ofmaterial layers is made in a preferred variant that way, that theindividual layers are rotationally symmetric. This is also possible, inparticular, if the layers are vertically oriented to the radialdirection, but also in a layer application in which the layers areobliquely oriented to the radial direction.

A further preferred measure is, that the build-up process comprisesseveral additive process steps, in order to successively build up thecomponent.

It is particularly preferred, if at least one further subtractiveprocess step is performed between the additive process steps. In thisfurther subtractive process step, the structure, which has been built upin the preceding additive process step, can be reprocessed, for exampleby milling, by grinding or by polishing. By this measure, surfaceoptimization can be realized or a particularly good geometric fidelitycan be achieved. It is especially preferred, that in each case onefurther subtractive process step is performed between two additiveprocess steps. That is to say, the additive process steps and thefurther subtractive process steps are performed alternately. This allowsa particularly high precision and surface quality of the component to beproduced.

Nowadays processing devices are known, with which additive processes,for example laser build-up welding, as well as also subtractiveprocesses, for example milling or grinding, can be performed. Suchdevices have different processing heads, for example, which areautomatically changeable, wherein one processing head is designed forlaser build-up welding, for example, whereas another processing head isdesigned for milling. Especially such processing devices allow a fastand easy change between subtractive and additive processing methodswithout the workpiece to be processed being re-clamped or transferredinto another processing station. This allows a particularly rapid,cost-effective and high-quality manufacturing of components, which areprocessed very precisely.

A possible variant is, that the component is built up part by part afterthe first subtractive process step, and wherein preferably first of allonly each separating wall is completed. Thus, for example, aftercompleting the first subtractive process step, at first all separatingwalls between the channels are completely built up and then the stillmissing parts are built up, e.g. those which turn the channels intoclosed channels.

It is particularly preferred for procedural reasons if the build-upprocess is performed by a laser. The method by laser build-up welding isparticularly suited for the build-up process.

The applications are particularly relevant for practical use, if thecomponent is designed as an impeller, as a guide wheel or as a diffusorof a rotary machine, in particular of a pump, of a turbine, of acompressor, of a compactor or of an expander.

It has been shown, that the method, according to the invention, also canbe very advantageously used in a corresponding similar manner forrepairing damaged or worn out components of a rotary machine. Accordingto this, the invention also proposes a method for repairing a componentof a rotary machine, which component extends in an axial direction aswell as in a radial direction vertical thereto, and comprising aplurality of inner channels, each of which extends from a first end inthe center of the component to a second end at the radial limitingsurface of the component, wherein adjacent channels are respectivelyseparated by a separating wall, wherein damaged areas of the componentat the limiting surface or at one of the channels or at one of theseparating walls are identified, in that furthermore a blank ismanufactured by a machining removal or by a separating removal of thedamaged areas, the blank comprising the center of the component andwherein the removed damaged areas are replaced by a build-up process onthe blank in order to manufacture the final form of the component.

Regarding the method, according to one embodiment of the invention, forrepairing a component, a blank is manufactured in a correspondingsimilar manner as in the method for manufacturing a component, on whichblank the missing parts or areas of the component subsequently aremanufactured by a build-up process. Regarding the method for repairing,the blank is generated by removing the damaged areas of the component.After manufacturing the blank by removing the damaged areas, the blankcorresponds to the blank manufactured by the method for manufacturingthe component, in principle, after performing the first subtractiveprocess step.

The component is a rotationally symmetric component for a plurality ofapplications. Regarding in particular the method for repairing, it isnot necessary, that the blank, generated by removal of the damagedareas, is also rotationally symmetric. For example, it may be possiblein the case of an impeller being the component, that the individualclosed channels or the individual separating walls between the channelsare damaged or worn out to a different degree, so that larger areas haveto be removed for a first channel rather than for another secondchannel. Regarding this, the blank is no longer rotationally symmetricafter removing all damaged areas.

The removal of the damaged areas can be made by a machining method, forexample by milling or by turning. Alternatively or complementary, it ispossible to remove the damaged parts by a separating process, forexample by punching, by cutting, by torch cutting or by sawing.

A further advantageous measure for the method for manufacturing acomponent as well as for the method for repairing a component is, thatat least one material is used for the build-up process, the materialbeing different from the material the blank is formed from. Regardingthe build-up process, one or more different materials or substances,respectively, can be used in order to optimize the properties of thecomponent in its predetermined areas in a selective way. It is possible,for example, to manufacture those areas of the component which areexposed to the highest loads in the operating state out of aparticularly hard or of a particularly wear-resistant or of aparticularly corrosion-resistant material. Regarding the impeller of apump, those particularly overloaded areas, for example, are the radialexterior parts of the separating walls (vanes) between the channels,thus the trailing edges of the vanes as well as the area of the radiallimiting surface of the impeller. These areas can be made of aparticularly wear-resistant material in the build-up process.

Of course, it is also possible to change the material during thebuild-up process, thus, for example, initially to use a material duringthe build-up process, the material being the same as the material of theblank, for example, and then using a different material thereof, forexample for the radial exterior areas of the component.

In this way it is also possible to generate a layer on individual partsby a build-up process, for example a wear protection coating.

Thus, due to this measure it is possible, for example, to realize ahigher hardness of the component at wear surfaces of the component in aselective way. Hereby the service life of the component is increased.Regarding the impeller of a pump, it is also in particular possible todo without a wear ring and to replace it by a coating, generated by thebuild-up process.

A component of a rotary machine is further proposed by the invention,the component being manufactured or repaired by a method according tothe invention.

According to a preferred embodiment, each separating wall is designed asa vane.

The applications are particularly relevant for practical use, if thecomponent is designed as an impeller, as a guide wheel or as a diffusorof a rotary machine, in particular of a pump, of a turbine, of acompressor, of a compactor or of an expander.

Further advantageous measures and designs of the invention resultembodiments disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail hereinafter withreference to the drawings.

FIG. 1 is a perspective view of an embodiment of a component accordingto the invention, the component being manufactured according to anembodiment of a method disclosed herein,

FIG. 2 is a perspective view of an embodiment of a blank for performingan embodiment of a method according to the invention,

FIG. 3 is a sectional view of the blank from FIG. 2 in a section in theaxial direction,

FIG. 4 is a perspective view of the blank from FIG. 2 after completingthe first subtractive process step, and

FIG. 5 is a sectional view of the blank from FIG. 4 in a section in theradial direction.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The method according to the invention is used for manufacturing acomponent of a rotary machine, the component having at least one innerchannel, extending out of a center to a limiting surface of thecomponent and which channel is at least partially closed. Here a closedchannel is a channel, which is completely closed, except for an inlet oran outlet, so the channel has a tubular shape, that is to say, thechannel is limited by one wall or by several walls anywhere, vertical toits main direction of flow. In contrast, an open channel means achannel, which is not limited by a wall in a direction vertical to itsmain direction of flow, thus in a direction vertical to its longitudinalextension, but it is open. So, for example, a channel with an U-shapedor a V-shaped wall is an open channel. If the open side of the U-profileor of the V-profile were covered with a plate, the channel would be aclosed channel.

A partially closed channel means a channel, which is partially designedas a closed channel and partially as an open channel.

In the following description of the invention it is referred to animportant example for practice with an exemplary nature, wherein thecomponent is a closed or a covered rotor (impeller), respectively, of aturbo engine, e.g. of a pump. For a better understanding, FIG. 1illustrates a perspective view of an embodiment of a component accordingto the invention, the component being a closed impeller and which isentirely provided with the reference sign 1. The impeller 1 can bemanufactured by a method according to the invention.

The component 1 or the impeller 1, respectively, extends in an axialdirection A as well as in a radial direction R vertical thereto. Theaxial direction A usually means that direction which is determined bythe axis of rotation of the rotary machine when the component 1 isinstalled in the rotary machine. The axis of rotation is that axisaround which the rotor of the rotary machine rotates in the operatingstate.

The impeller 1 rotates around the axis of rotation in the operatingstate, which axis determines the axial direction A. A direction verticalto this axial direction A is described as radial direction R.

The impeller 1 is a rotationally symmetric component with respect to theaxial direction A and comprises a shroud 2 in a manner known per se,with which the impeller 1 usually is mounted or fixed on an axis or ashaft, not shown here, and also a number of vanes 3, which are arrangedon the shroud 2, as well as a cover plate 4 covering the vanes 3 atleast partially at the side or edge, respectively, facing away from theshroud 2. According to the description (FIG. 1), the cover plate 4extends higher than the shroud 2 with respect to the axial direction A.

As a result according to the description, an internal space 6 is formedabove the vanes 3, the space being limited by the cover plate 4 withrespect to the radial direction R. This internal space 6 presents theinlet in the operating state, through which the fluid flows to theimpeller 1. An inner channel 7 exists in each case between two adjacentvanes 3, which channel is designed as an at least partially closedchannel 7 and here as a closed channel 7.

Each channel 7 extends from a first end 72 in a center of the impeller1, which is formed by the internal space 6, to a respective second end71 in a limiting surface 42 of the impeller 1. The limiting surface 42presents the radially outer surface of the impeller 1, which surfaceextends parallel to the axial direction A, that is to say, the surfacelimiting the impeller 1 outwards in the radial direction R. “Parallel tothe axial direction A” means, that each vector of the surface normal ofthe limiting surface 42 is vertical on the axial direction A. Thelimiting surface 42 comprises the radially outer surfaces of the coverplate 4 and of the shroud 2 as well as the radially outer closing edgesof the vanes 3, which are called trailing edges 31.

Thus adjacent channels 7 are each separated by a separating wall 3, eachseparating wall 3 forming in each case one vane 3 of the impeller 1.

Depending on the design of the impeller 1 it is also possible, that theclosing edges of the vanes 3 are displaced backward with respect to theradial direction, that means they are not in the limiting surface 42.Then, the cover plate 4 and/or the shroud 2 protrudes over the vanes 3or the closing edges of the vanes 3, respectively, with respect to theradial direction R. Such a design particularly is also possibleregarding a rotor of a turbine, where the outer closing edges of thevanes 3 usually are the leading edges.

Hence, each of the closed channels 7 is enclosed by a limiting surface8, in each case composing of the surfaces of two adjacent vanes 3 facingeach other, as well as of the intermediate surface segments of thesurfaces of the shroud 2 and of the cover plate 4 facing each other,which surface segments forming the bottom and the top of the respectchannel 7. Thus, the vanes 3 each form a separating wall between twoadjacent inner channels 7. The second end 71 of each channel 7 comprisesthe port, with which the respective channel 7 joins the limiting surface42. Adjacent second ends 71 in a peripheral direction are separated fromeach other by a trailing edge 31.

The impeller 1 also has a central through bore 9, which is used toreceive a shaft or an axis, on which the impeller 1 is mounted.

An embodiment of the method according to the invention is explained inmore detail below with reference to FIG. 2-5.

According to the method of an embodiment of the invention a blank isfirst provided. FIG. 2 illustrates in a perspective view an embodimentof such a blank, which is entirely provided with the reference sign 10.This blank 10 is designed for manufacturing the impeller 1, illustratedin FIG. 1. For a better understanding, FIG. 3 illustrates a sectionalview of the blank 10 from FIG. 2 in a section in the axial direction A.

The blank 10 is a particularly preferred designed in a rotationallysymmetric way with respect to the axial direction A, as also illustratedin FIG. 2 and FIG. 3.

The blank 10 has the central through bore 9, which is used to receivethe shaft or the axis, on which the impeller 1 can be mounted. The bore9 is limited in the area of its upper end (illustrated in FIG. 2) by anannular body 21, coaxially extending about the axial direction A. Thisannular body 21 forms a part of the shroud 2 in the finished state ofthe impeller 1.

The blank 10 further comprises the center formed by the internal space6, which center presents the inlet of the impeller 1 in the operatingstate, through which the fluid flows to the impeller 1. The internalspace 6 is designed as a cavity in the blank 10, which cavityrotationally symmetric and coaxially extends about the annular body 21.This cavity is radially inside limited by the annular body 21. Regardingthe radial direction R external, the cavity forming the internal space 6is limited by a cylindrical area 41, as well as by a substantiallycone-mantle-shaped wall 61 joining the cylindrical area 41 below(illustrated in FIG. 3) in the axial direction A. The cylindrical area41 as well as the wall 61 are coaxially arranged to the bore 9 and arerotationally symmetric regarding the axial direction A. The cylindricalarea 41 forms a part of the cover plate 4 in the finished impeller 1(see FIG. 1), namely that part limiting the internal space 6 in theradial direction.

The blank 10 is limited by an outer surface 11 in the radial directionR, which outer surface 11 is designed to be cylinder-mantle-shaped inthis embodiment and which extends coaxially to the bore 9 about theaxial direction A. Consequently, the dimension of the outer surface 11in the radial direction R is the diameter D1 of thecylinder-mantle-shaped outer surface 11.

Naturally, such designs are also possible, wherein the radially externalouter surface 11 of the blank 10 is not a cylinder mantle surface, buthas another geometrical design, for example having the shape of a conemantle surface or of a truncated cone mantle surface. In such cases, D1indicates the maximum dimension of the outer surface 11 in the radialdirection R, thus the maximum diameter, for example, which is enclosedby the outer surface 11.

The maximum dimension of the blank 10 in the axial direction A isdescribed with the height H1. The height of the outer surface 11 of theblank 10 in the axial direction A may be smaller than or equal to thisheight H1.

The blank 10 is designed in such a way, that the diameter D1 of itsouter surface 11 is smaller than the corresponding dimension of thelimiting surface 42 in the radial direction R. The dimension of thelimiting surface 42 in the radial direction R is the outer diameter D2of the impeller 1 (see FIG. 1). Thus it is D1<D2.

The height H2 of the impeller 1 in the axial direction A (see FIG. 1) isits maximum extension in the axial direction A.

In this embodiment, the height H1 of the blank 10 is measured such, thatthe height is equal to the height H2 of the finished impeller, thus itis H1=H2.

Of course, it can also be advantageous to measure the height H1 of theblank 10 smaller than the height H2 of the finished impeller. Forexample, a suitable choice of H1 can be made on the basis of thecriterion how much volume of the component 1 is to be manufactured by abuild-up process and which parts of the component 1 are to bemanufactured already in the first subtractive process step. Of course,this depends on the specific geometry of the component 1 to bemanufactured and on economic factors.

The outer surface 11 of the blank 10 is preferably designed as acoherent surface having no openings.

Particularly preferred, the blank 10 is made of a forged material, whichmay be a metal or a metal alloy. Thus, for example, steel is suitable inits known embodiments or aluminum, titanium, nickel, a nickel or cobaltbase alloy or a non-ferrous metal. Of course, other than forgedmaterials are also possible, for example a cast material, a syntheticmaterial or a composite or another machinable material.

The blank 10 is preferably manufactured or processed in such a way, thatparts of the shroud 2 as well as of the cover plate 4 are alreadydesigned in its desired final form or at least substantially in itsfinal form. In that regard, “substantially” means that, of course,post-processings can be performed at a later stage, as for examplemilling, turning, grinding, polishing or something similar, but thesubstantial design is already completed in the blank 10. Preferably, atleast the following parts of the blank 10 are designed that way, thatthey substantially have the final form of the completed impeller: thecentral axial bore 9, the annular body 21 as a part of the shroud 2, thecylindrical area 41 as a part of the cover plate 4, the internal space6, which forms the center and which is realized by the cavity in theblank 10. Furthermore, in the embodiment described here, the height H1of the blank 10 is already substantially identical to the height H2 ofthe impeller 1.

Now a first subtractive process step is performed on this blank 10,which process step is explained below. FIG. 4 illustrates a perspectiveview of the blank 10 after finishing the first subtractive process step.Particularly, the first subtractive process step is performed by amachining process. For a better understanding, FIG. 5 additionallyillustrates a sectional view of the blank from FIG. 4 in a section inthe axial direction A.

A subtractive process step means, that material is cut or removed,respectively, from the workpiece—here from the blank 10—in such aprocess step. As it is generally usual, a machining process means aprocess wherein excessive material is removed from the blank 10 or theworkpiece, respectively, in the form of chips in order to achieve adesired geometrical form. For example, machining processes are milling,turning, drilling, planing, filing, grinding, honing or lapping, tomention only a few examples.

The first subtractive process step preferably comprises milling by amachining device, comprising, for example a computer-controlled millingtool. Particularly preferred, the machining device is designed at leastas a five-axes-milling tool, with which the desired geometrical form iselaborated out of the blank 10. The milling tool is usually guided by amanipulator, the guide being computer-assisted.

One part is manufactured from each channel 7 in the first subtractiveprocess step, which part extends from the first end 72 of the respectivechannel into the outer surface 11 of the blank 10. The first end 72 ofeach channel 7 joins the wall 61, limiting the internal space 6.

As it particularly is illustrated in FIG. 4, the area of the port ofeach channel 7 into the outer surface 11 is designed as a closed channelsection. These ports are each milled into the outer surface 11, whereinadjacent ports each are separated from each other by an edge 32 of theincomplete separating walls 3.

After the ports of the channels 7 into the outer surface 11 of the blank10 have been finished, the outer surface 11 has a coherent annular area12 covering the port of each channel 7 into the outer surface 11. Thus,all channels 7 are closed by the annular area. That is, after finishingthe first subtractive process step (see FIG. 4), the outer surface 11 ofthe blank 10 comprises the annular area 12, which surface is designed asannular coherent area having no openings, and thus being consistent withrespect to the peripheral direction, and which area covering all portsof the channels 7 into the outer surface 11.

The parts of each channel 7 being manufactured in the first subtractiveprocess step, that means in each case the channel section from the firstend 72 of the channel in the wall 61 of the internal space 6 to the portof the respective channel into the outer surface 11 of the blank 10, arepreferably manufactured in such a way, that they substantially have atleast their final form.

After finishing the first subtractive process step (see FIG. 4, FIG. 5)the blank 10 has the following form: the center formed by the internalspace 6, the bore 9, the annular body 21 and the cylindrical area 41 ofthe cover plate 4 substantially have at least their final form. Thatpart of each channel 7 is completed, i.e. substantially in its finalform, which extends from its first end 72 joining the internal space 6to the port into the outer surface 11 of the blank 10. Thus, the blank10 already has at least substantially the final form of the completedimpeller 1 apart from those areas of the impeller 1, which are arrangedradially external with respect to the outer surface 11 of the blank 10.

It is understood, that the first subtractive process step can comprise amilling from the wall 61 or from the internal space 6, respectively, aswell as a milling from the outer surface 11. Of course, it is alsopossible, to mill or to process by machining, respectively, only fromthe internal space 6 or only from the outer surface 11 in the firstsubtractive process step depending on the component.

It is an advantage of the purely machining process, that a blank 10 madeof a forged material retains all positive properties of the forgedmaterial.

It is understood, that the diameter D1 of the blank 10, which inprinciple is a freely selectable parameters within wide limits,preferably is chosen such in the respective application, that theseparts of the channels 7 manufactured in the first subtractive processstep can be elaborated out of the blank 10 by machining without anyproblem, for example by milling, in particular with respect to thegeometry.

After finishing the first subtractive process step (see FIG. 4, FIG. 5),the still missing parts of the component 1 are manufactured by abuild-up process and the component 1 is brought in its final form. FIG.1 illustrates in a perspective view the finished component 1, here thecovered impeller 1, which is manufactured out of the blank 10,illustrated in FIGS. 4 and 5.

A build-up process means a process, wherein a shapeless or a neutrallyshaped material is applied. In doing so, the shapeless material, forexample a powder, or the neutrally shaped material, for example astrap-shaped material, usually is melted in order to build up the stillmissing parts of the component 1 on the blank or on the already existingstructure, respectively. Thus, a build-up process is a process out of ashapeless or a neutrally shaped material.

The build-up manufacturing comprises one or several additive processstep(s). An additive process step or an additive manufacturing, which isalso referred to as generative manufacturing, respectively, means aprocess step, wherein material is added or applied on the workpiece,here the blank 10. The desired structures usually are generated, forexample by a build-up process on a workpiece, in an additivemanufacturing out of a shapeless material, for example liquids orpowders, or out of a neutrally shaped material, for example strap-shapedor wire-shaped material, by chemical and/or physical processes. Additivemanufacturing methods known per se for metallic workpieces are, forexample build-up welding methods, in particular inert gas methods astungsten inert gas welding (TIG) or laser build-up welding or plasmamethods or selective laser melting (SLM selective laser melting) orselective laser sintering (SLS).

After finishing the first subtractive process step the still missingareas of the component 1 are generated by a build-up process, inparticular these are the radial exterior parts of the separating walls 3and of the channels 7, parts of the cover plate 4 as well as parts ofthe shroud 2.

In a preferred embodiment, the still missing parts are generated in thebuild-up process by laser build up welding. The method of laser build-upwelding with its different variants is well known to the person skilledin the art and, thus, no further explanations are required.

Hence, it is possible to perform the build-up process of the blank 10layer by layer, in particular by using the rotationally symmetricdesign.

Another preferred embodiment is to build up the component 1 part by partin the build-up process, i.e. the individual parts of the component 1 ase.g. the separating walls 3 or the covers of the channels 7 aresuccessively built up in this sense, that first a part, e.g. theseparating walls, is completely built up to its final state and then thenext part is completely built up. This process is repeated until thecomponent is finished.

Furthermore, it is possible, that the individual parts of the component1 are not completely built up, but only part by part, in other wordsfirst a part of the separating walls 3 is built up, then a part of thecovers of the channels 7, then a part of the separating walls 3 againand so on. In doing so, a further subtractive process step canpreferably be performed after a partial build up.

As already mentioned, according to a preferred embodiment the build-upprocess can comprise several additive process steps to build up thecomponent 1 in a successive manner. Regarding this, it is particularlypreferred performing at least one further subtractive process stepbetween the additive process steps.

Deviations from the desired geometry can be compensated in such afurther subtractive process step, for example by a machining process,which deviations have arised in the preceding additive process step.Thus, for example, milling or grinding works can be performed in thisfurther subtractive process step, in order to remove such material whichwas applied too much in the additive process step or in order toequalize or to grind junctions between adjacent layers or the like.

It is particularly preferred performing a further subtractive processstep in each case between two additive process steps, i.e. the additiveprocess steps and the further subtractive process steps are performedalternately or in turns, respectively. This ensures a particularly highquality and precision of the component 1.

Nowadays modern processing machines are known, with which subtractiveprocess steps as well as additive process steps can be performed in thesame process chamber without need to re-clamp the blank 10 or thecomponent 1, respectively, or to put them into another holder. The blank10 is only once clamped into a holder and then, the blank can beprocessed selectively or alternately in a subtractive or additivemanner. Such processing machines comprise several processing heads forthis purpose, at least one of them being designed for a subtractiveprocess, for example as a milling tool, and at least one of them beingdesigned for the additive process, for example as a device for laserbuild up welding. After finishing an additive process step, for example,the processing machine automatically changes the processing head andthen it can perform a subtractive process step and vice versa. In doingso, a particularly fast and very precise manufacturing of the component1 is possible.

Deviating from the embodiment described above, it is also possible,according to another also preferred variant, that parts of the annularbody 21 and/or of the cylindrical area 41 are only manufactured in theadditive process.

Thus, it is possible, for example, to manufacture the upper zoneaccording to the illustration (FIG. 5) of the cylindrical area 41 onlyafter the first subtractive process step in regard to the build-upprocess, having the advantage, that parts of the channel 7, which are tobe elaborated in the first subtractive process step, are more accessibleto the tool. The “upper zone” means that part of the cylindrical area41, which is, according to the illustration, above the first ends 72 ofthe channels 7 with respect to the axial direction A.

Alternatively or additionally, it is also possible, that a part of theannular body 21 is only manufactured in regard to the build-up process.This also makes it possible to ensure a better accessibility to theports of the channels 7 in the first subtractive process step, whichchannels are elaborated out of the blank 10 in this first subtractiveprocess step.

The invention also proposes an analogously same method for repairingdamaged or worn out components of a rotary machine. Regarding the methodfor repairing a components 1 of a rotary machine, for example theimpeller 1 of a pump, it is proceeded in the analogously same manner asdescribed above, but the blank 10 is generated out of a damaged or wornout, respectively, impeller 1. For example, this can be an impeller 1,whose trailing edges 31 of the vanes 3 or of the separating walls 3,respectively, or the radially outer areas of the channels 7 are damaged.The method according to the invention for repairing the component isparticularly characterized in that damaged areas of the component 1 areidentified at the limiting area 42 or at the channels 7 or at aseparating wall, that further a blank 10 is manufactured by a machiningor by a separating removal of the damaged areas, which blank comprisingthe center of the component 1, and that the removed damaged areas arereplaced by a build-up process on the blank in order to manufacture thefinal form of the component 1.

Regarding the method according to the invention for repairing acomponent the blank 10 is manufactured in an analogously same manner asin the method for manufacturing a component, on which blank the stillmissing parts or areas of the component 1 are subsequently manufacturedby a build-up process.

Regarding the method for repairing, here the blank 10 is generated byremoving the damaged areas of the component. After manufacturing theblank 10 by removing the damaged areas, the blank corresponds inprinciple to the blank 10 manufactured by the method for manufacturingthe component after performing the first subtractive process step (seeFIG. 4 and FIG. 5).

Regarding the method for repairing, it is particularly not necessary,that the blank generated by removing the damaged areas is rotationallysymmetric. For example, in the case of an impeller 1 being thecomponent, it can be possible, that the individual closed channels 7 orthe individual separating walls 3 between them are differently damagedor worn out, so that larger areas have to be removed from a firstchannel 7 than from another second channel 7. In this case, the blank 10is no longer rotationally symmetric after removing all damaged areas.

The removal of the damaged areas can be performed by a machining method,for example by milling. Alternatively or additionally, it is alsopossible to remove the damaged areas by a separating process, as forexample punching, cutting, torch cutting or sawing.

The illustrations regarding the method for manufacturing the component 1including the advantageous measures and variants are also valid in asame or in an analogously same manner for the method for repairing thecomponent 1.

Regarding the method according to the invention for manufacturing acomponent as well as the method according to the invention for repairinga component, it is possible to use one ore several materials for thebuild-up process, the materials being different from the material ofwhich the blank is consisting. Of course, it is also possible to changethe material during the build-up process, thus using different materialsfor the build-up process, for example up to four different materials.Thus, for example, a first material can be used for a first additiveprocess step, the material being equal or different from the material ofthe blank 10 and then using a second material for a further additiveprocess step, the material being different from the first material.

In this way, layers can be generated, for example wear protectivecoatings for protecting particularly such areas of the component wherethe highest loads arise in the operating state. Here such coatings canbe generated directly on areas, which are manufactured in thesubtractive process step, as well as on areas, which are generated in apreceding additive process step.

In this way, areas of the component can be optimized specifically withrespect to hardness, wear resistance, corrosion resistance and so on.

Regarding the impeller of a pump it is possible, for example, theradially external areas of the separating walls (vanes) between thechannels, hence the trailing edges of the vanes as well as the area ofthe radial limiting surface of the impeller. Then, these areas can bemanufactured out of a particularly wear-resistant material in thebuild-up process.

Of course, it is also possible to change the material during thebuild-up process, thus, for example, initially using a material duringthe build-up process, the material being the same as the material of theblank, for example, and then using a different material, for example forthe radially exterior areas of the component.

In this way, it is also possible to generate a layer on individual partsor areas of the component by a build-up process, for example a wearprotection coating.

Thus, due to this measure it is possible, for example, to realize ahigher hardness of the component at wear surfaces of the component in aselective way. Hereby the service life of the component is increased.Regarding the impeller of a pump it is also in particular possible to dowithout a wear ring, which may be disposed on the impeller, and toreplace the wear ring by a coating, generated by the build-up process.

Although the invention has been explained with reference tomanufacturing or repairing, respectively, an impeller 1, the inventionis, of course, not limited to such components 1 or their manufacturingor their repairing, respectively, but the invention is suitable for aplurality of other components 1, in particular for such components 1where at least one inner channel 7 is provided, which geometry does notallow to elaborate that channel by machining or subtractively out of ablank 10 with a reasonable expenditure.

In particular, the component 1 can also be designed as an impeller or asa diffusor of a rotary machine, wherein the rotary machine can be inparticular a pump or a turbine or a compressor or a compactor or anexpander.

The inner channel can also be, for example, a cooling channel, e.g. in aturbine blade, for example a cooling air channel.

1. A method for manufacturing a component of a rotary machine, thecomponent extending in an axial direction and a radial directionvertical thereto, and having at least one inner channel extending from afirst end in a center of the component to a second end at a radiallimiting surface of the component and which is at least partiallyclosed, that the method comprising: providing a blank, comprising thecenter of the component, and the blank being limited by an outer surfacein the radial direction, the maximum dimension of the outer surface inthe radial direction being smaller than a dimension of the limitingsurface in the radial direction; performing a first subtractive processstep in which a part of the channel is manufactured by a machiningprocess, with the part extending from the first end of the channel tothe outer surface of the blank; and afterwards finishing the channel bya build-up process on the blank.
 2. The method according to claim 1,wherein the component the at least one inner channel includes aplurality of inner channels, each of the plurality of inner channelsextending from a first end in the center of the component to a secondend at the radial limiting surface of the component, adjacent channelsare respectively separated by a separating wall, and for each channel,one part of the channel is manufactured in the first subtractive processstep, with the part extending from the respective first end of thechannel into the outer surface of the blank, and each separating walland each channel is only finished by the build-up process.
 3. The methodaccording to claim 1, wherein the blank has a central bore before thefirst subtractive process step, the bore being arranged radiallyinwardly such, that in the finished state of the component each firstend of a channel arranged in the center is separated from the centralbore by an annular body.
 4. The method according to claim 1, wherein thefirst subtractive process step is performed in such a manner, that afterfinishing the outer surface of the blank, the blank comprises acontiguous annular area covering the confluence of each the channel intothe outer surface.
 5. The method according to claim 1, wherein thebuild-up process is performed layer by layer.
 6. The method according toclaim 1, wherein the build-up process comprises several additive processsteps to successively build up the component.
 7. The method according toclaim 6, wherein at least one further subtractive process step isperformed between the additive process steps.
 8. The method according toclaim 6, wherein in each case one further subtractive process step isperformed between two additive process steps.
 9. The method according toclaim 1, wherein the component is built up part by part after the firstsubtractive process step.
 10. The method according to claim 1, whereinthe build-up process is performed by a laser.
 11. The method accordingto claim 1, wherein the component is an impeller, a guide wheel or adiffusor of a rotary machine.
 12. A method for repairing a component ofa rotary machine, the component extending in an axial direction and aradial direction vertical thereto, and comprising a plurality of innerchannels, each inner channel extending from a first end in a center ofthe component to a second end at a radial limiting surface of thecomponent, adjacent channels being respectively separated by aseparating wall, the method comprising: identifying damaged areas of thecomponent at the limiting surface or at one of the channels or at one ofthe separating walls; manufacturing a blank by a machining removal or bya separating removal of the damaged areas, the blank comprising thecenter of the component; and replacing the removed damaged areas by abuild-up process on the blank to manufacture the final form of thecomponent.
 13. The method according to claim 1, wherein at least onematerial is used for the build-up process, the material being differentfrom the material of the blank.
 14. A component of a rotary machinemanufactured or repaired with a method according to claim
 1. 15. Thecomponent according to claim 14, wherein the component is an impeller, aguide wheel or as a diffuser of a rotary machine.
 16. The methodaccording to claim 9, wherein during the build up part all of eachseparating wall is completed first.
 17. The method according to claim11, wherein the component is part of a pump, a turbine, a compressor, acompactor or an expander.
 18. The method according to claim 15, whereinthe component is part of a pump, a turbine, a compressor, a compactor oran expander.